Subsea industrial and scientific installations have seen significant growth in recent years and wired data networks are now being installed to support these activities.
Multi-cored conductive umbilical cables have been used historically to support wired data communications. Fibre optic based network systems are also an established method of carrying data under water. Submarine fibre optic cables are capable of greater single hop distances between repeaters than electrical conductive cable based systems and are not subject to single point failure through water penetration of an insulating jacket in the same way that conductive cables are. Single fibres are also capable of supporting much higher data transmission rates than a single conductive link. Conductive wires and optical fibres can both be classed as cabled networks.
Cabled underwater networks have operational limitations that are particular to their deployment in the underwater environment. Communications access points have to be designed in and manufactured ahead of cable deployment since cutting and splicing a connection is not practical underwater. This is often inconvenient when changing circumstances result in the need to implement additional connections. Even where a connector has been provisioned close to the desired communication point the type of connection may not allow expansion of the number remote client systems accessing the cabled network through the available connector.
Fault finding is also problematic under water since submerged cables cannot be probed to test continuity in the way that above water cable links are commonly tested.
In contrast wireless underwater communications systems, implemented through acoustic or radio carriers, avoid many of these practical limitations. However, wireless underwater communications systems cannot at present support broadband long range communications and cannot deliver electrical power.
There is need for an underwater communications system which combines the operational benefits of cabled and wireless systems.